-LRB- CNN -RRB- -- Andy Murray 's birthday celebrations were brought to an abrupt halt after his plans to compete at the French Open were thrown into jeopardy on Wednesday .

A long-term back injury looks set to sideline the world No. 2 , who was forced to retire from his second-round match at the Rome Masters on the day he turned 26 .

And with the Paris showpiece event set to begin on May 26 , Murray faces a race against time to prove his fitness .

`` I 'd be very surprised if I was playing in Paris , '' the British star , who lost in the quarterfinals in Madrid last week , told reporters following his match against Spain 's Marcel Granollers .

`` I felt pain today , the same as in Madrid . I took a few days off after Madrid . I hit yesterday and played some points . But I was still sore today . ''

The pain in the lower left of his back has caused Murray discomfort since late 2011 and is the same injury which required a painkilling injection at last year 's French Open .

`` We will have to wait and see on Paris , '' he said . `` I 'll try to make a decision after the next five days or so . I need some days off for it to hopefully settle down . ''

Murray 's retirement came as something of a surprise after he had fought back from losing the opening set 6-3 and being down 4-1 in the second to level the match following a tiebreak .

But after undergoing on-court treatment with the trainer early in the second set , Murray decided to call time on his Rome challenge .

It is the first time since 2007 that Murray has retired during a contest -- that was at the Hamburg Open where he suffered a wrist injury which ruled him out of the French Open and Wimbledon .

Murray , who has never won a clay-court title despite training on the surface as a young teen in Spain , reached the quarterfinals at Roland Garros last year .

But the U.S. Open and Olympic champion now looks unlikely to challenge for the title in the French capital .

'' -LRB- The back -RRB- has not been perfect for a long period , I want it to start feeling good again , '' the Scot said .

`` Everyone goes into matches with niggles , but this is very frustrating .

`` Some shots hurt more on clay because the movement is so exaggerated . There is not a lot of power on the ball so you have to generate power and pace yourself .

`` I do n't want to go into details , but I 've got a disc problem , it changes week to week . It 's been an issue for a while , but I want to make sure it goes away .

`` I do n't want to be playing with it long term , it 's not enjoyable at all . ''

Elsewhere , French eighth seed Jo-Wilfried Tsonga suffered a shock defeat by Jerzy Janowicz , going down 6-4 7-6 . The 24th-ranked Pole ripped his shirt off in delight after his best result this year , earning a clash with French ninth seed Richard Gasquet .

In the women 's section , defending champion Maria Sharapova eased to a 6-2 6-2 win over Spain 's Garbine Muguruza .

Former French Open winner Li Na overcame Chinese compatriot Zheng Jie 6-3 6-1 as she bounced back from her first-round defeat in Madrid , while there were also victories for Samantha Stosur , Maria Kirilenko and home favorite Roberta Vinci .

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Andy Murray faces a race against time to be fit for French Open

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World No. 2 forced to retire with back injury at Rome Masters

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Murray says injury is the same as that has haunted him since late 2011

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Tournament at Roland Garros gets underway on May 26